Container accommodating an object

ABSTRACT

There is provided a container which can accommodate an object inside an internal space shaped by an inner surface of the container. The inner surface substantially has a shape of a sphere, a semiregular polyhedron or a dual polyhedron of a semiregular polyhedron. The inner surface is formed by plural segmented members made of a refractory material.

TECHNICAL FIELD

The present invention relates to a container which can accommodates an object such as liquid, for example, a container which can accommodate a molten metal such as a metal or an alloy of the metals such as aluminum, magnesium, and zinc inside the container.

1. Background Art

A casting process has a feature in which a shape can be easily given to a product. The casting process is a basic technology in manufacturing many mechanical components for an automobile or the like. An ordinary casting process includes steps of melting a casting material (raw material), filling a container with a molten material (molten metal), carrying the container to a casting apparatus, and casting the molten metal with the casting apparatus.

Ordinarily, a container used for delivering the molten metal constantly has a problem of a dissipative heat loss. Heat of the molten metal filling the container is externally dissipated via a wall constituting the container. Therefore, the temperature of the molten metal inside the container decreases while the container is carried, and the molten metal having a predetermined temperature is not obtainable after starting casting. In view of the energy loss, the dissipative heat loss greatly affects an entire casting process. In this case, when casting is started, it is necessary to raise the temperature of the molten metal filling the container to be an excessively high temperature in advance in order to obtain a molten metal having a predetermined temperature. With this, energy consumed in an entire process greatly increases.

In order to suppress a dissipative heat loss, there is an example that a cavity causing a reduced pressure is provided on a wall surface constituting a container (Patent Document 1).

2. Related Art

-   [Patent Document 1] Japanese Laid-open Patent Publication No.     2001-340957.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

However, a container disclosed in Patent Document 1 has a problem that a relationship between a contact area in contact with a heat source and heat transmission inside the container is not considered.

Generally speaking, heat may be transferred more easily as the area in contact with the heat source increases. Therefore, a dissipative heat loss is apt to be generated. However, the contact area of the container of Patent Document 1 is relatively large inside an internal space of the container. Therefore, an effect of suppressing dissipative heat transfer is insufficient in the container.

The present invention is described under the background. The object of the present invention is to provide a container for accommodating a liquid which can suppress a dissipative heat loss.

Means for Solving Problems

Accordingly, a mode of the present invention may provide a container which can accommodate an object inside an internal space shaped by an inner surface of the container, wherein the inner surface substantially has shapes of a sphere, a semiregular polyhedron or a dual polyhedron of a semiregular polyhedron, and the inner surfaces are formed by a plurality of segmented members made of a refractory material.

The refractory material of the container may be a refractory metal or a refractory alloy.

Another mode of the present invention may provide a container which can accommodate an object inside an internal space shaped by an inner surface, wherein the inner surface substantially has a shape of sphere, a semiregular polyhedron, or a dual polyhedron of semiregular polyhedron, and the inner surface is formed by a plurality of segmented members made of a ceramic.

It is preferable in the container to cause a value of S/V (m) to be lower than 7.7 m⁻¹ wherein a value of S/V (m) is lower than 7.7 m⁻¹ where a volume of the internal space is V (m³) and a surface area of the inner surface is S (m²).

The semiregular polyhedron may be substantially configured by a combination of an equilateral triangle and an equilateral pentagon.

The dual polyhedron of the semiregular polyhedron may be a pentagonal hexecontahedron, a deltoidal hexecontahedron, or a hexakis icosahedron.

The segmented members may have a first main surface of a curved face and a second main surface of a curved face, the first and second main surfaces being substantially parallel each other.

The segmented members may have a cavity.

The ceramic forming the segmented member may be made of one or more materials selected from a group of aluminum titanate silicon nitride, cordierite, spodumene, alumina, silicon carbide, zirconia, sialon, mullite, and boron compound.

The ceramic forming the segmented member may be a refractory brick including one or more materials selected from a group of alumina, magnesia, chromia, silica, and calcia.

A first inorganic filler may be set between the segmented members in the container.

A sheet material including an inorganic fiber may be provided between the segmented members of the container.

The inorganic fiber included in the sheet member may include alumina.

The container of the present invention further includes a casing covering the inner surface, and a second inorganic filler may be supplied between the casing and the inner surface.

The container further includes a casing surrounding the segmented member, and a sheet material including the inorganic fiber may be installed between the casing and the segmented member.

Alumina may be contained in the inorganic fiber of the sheet material.

The container may be used to accommodate the molten metal.

A material different from a material forming the segmented member may be installed on at least one surface of the segmented members in the container.

A ceramic may be installed on at least one surface of the refractory materials in the container.

The internal space may be a space substantially hermetically-closed in the container.

In the container, an introduction spout for introducing an object into the internal space and a discharge spout for discharging the object from the internal space may be the same.

Effect of the Invention

According to the present invention, it is possible to provide a container for accommodating a liquid which can suppress a dissipative heat loss.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view schematically illustrating a container according to the present invention.

FIG. 2A is a plan view illustrating an example of a segmented member forming the inner surface of the container of the present invention.

FIG. 2B is a side view illustrating an example of the segmented member forming the inner surface of the container of the present invention.

FIG. 2C is a bottom view illustrating an example of the segmented member forming the inner surface of the container of the present invention.

FIG. 3 illustrates an example arrangement of segmented members for forming an inner surface.

FIG. 4 is a cross-sectional enlarged view for illustrating a container of the embodiment of the present invention.

FIG. 5 illustrates an example arrangement of other segmented members for forming an inner surface.

FIG. 6 illustrates an example arrangement of other segmented members for forming an inner surface.

FIG. 7 illustrates an example arrangement of other segmented members for forming an inner surface.

FIG. 8 is a graph illustrating a change of a surface area of a “cylindrical container” relative to the radius r₁ of the bottom surface of the “cylindrical container”.

FIG. 9 is a graph illustrating a change rate P of the surface area S₁ of the cylindrical container relative to the surface area S₂ of the “substantially sphere-like container” as a function of the radius r₁ of the bottom surface of the cylindrical container.

FIG. 10 is a cross-sectional view for schematically illustrating another container of the embodiment of the present invention.

FIG. 11A schematically illustrates a shape of an example, segmented member according to Embodiment 9.

FIG. 11B schematically illustrates a shape of the example segmented member according to Embodiment 9.

FIG. 11C schematically illustrates a shape of the example segmented member according to Embodiment 9.

FIG. 12 schematically illustrates a cross-sectional view of the container of Comparative Example 1.

BEST MODE FOR CARRYING OUT THE INVENTION

A description is given below, with reference to FIG. 1 through FIG. 12 of the present invention.

First Mode

FIG. 1 illustrates a schematic cross-sectional view of an example container 100 which can accommodate a liquid like a molten metal.

The container 100 has a casing 105 formed by a metal such as stainless steel. Plural segment members 110 to be described in detail later are arranged on an inside of the casing. An inner surface 130 of the container 100 is formed by the segmented members 110. The inner surface 130 of the container 100 forms the internal space 135 of the container and is directly in contact with molten metal accommodated in the container 100. The casing 105 is not directly in contact with the molten metal because of the existence of the segmented members 110 and the inorganic filler 107. The segmented members 110 may be made of a ceramic. Alternatively, the segmented members 110 may be formed by a refractory metal, a refractory alloy, or the like.

In the present invention, the terminology “ceramic” is a broad concept including all inorganic materials excluding metallic materials and organic materials; said differently, fine ceramics, composite materials including inorganic materials, refractory brick and so on.

Although it is not illustrated in figures, another coating such as an inorganic fiber coating may be provided between the casing 105 and the inorganic filler 107 and/or between the inorganic filler 107 and the segmented member 110. However, a description of the coating is omitted because the coating is known.

As a feature which is not essential for the present invention, the container 100 includes a top lid 150. The molten metal can be supplied in an internal space 135 of the container 100 by opening the top lid 150. The top lid 150 is formed by a casing 105, an inorganic filler 107 and a segmented member 110 in a manner similar to other parts of the container 100. The top lid 150 can be freely opened and closed by, for example, a known hinge mechanism 152. When the top lid is closed, the internal space 135 is hermetically closed. Said differently, when the top lid 150 is closed, the inner surface 130 of the container is continuously formed. A discharge spout 160 is provided at an appropriate portion of the container 100 to enable outwardly ejecting the molten metal. Referring to FIG. 1, the discharge spout 160 is formed by the casing 105, the inorganic filler 107 and the segmented member 110 in a similar manner to the other portions of the container 100. The discharge spout 160 may be formed by a combination of other members. Although it is not illustrated in figures, a seat may be provided on a bottom surface of the container 100 in order to stabilize an installed condition of the container 100.

The container 100 has a feature in which the inner surface 130 of the container 100 has a relatively small surface area in comparison with the volume of the container 100.

Generally speaking, the following relationship may be established between a surface area of a member in contact with a heat source (high temperature fluid) and a heat quantity (amount of heat transmission) which is transmitted via the member.

Q=hA(θf−θw)  (1)

, where Q designates the amount of heat transmission, A designates the surface area of the member, θw designates the temperature of the member, and θf designates the temperature of the heat source (high temperature fluid). Further, h designates the coefficient of heat transfer, the unit of which is W/m²·K(kcal/m·h·° C.). It is possible to know that the smaller the surface area A of the member, the smaller the amount of heat transmission Q.

The inventors of the present invention have found that this principle can be used in forming the container 100. According to the present invention, it becomes possible to significantly restrict dissipation loss in the container in comparison with a conventional container. As described later, in comparison with the conventional container having a similar volume, the inner surface area 130 of the container of the present invention may have a smaller surface area.

In order to form the inner surface 130 of the container having the small surface area, plural segmented members 110 are put together to cause the inner surface to be shaped substantially like a sphere, a semiregular polyhedron, or a dual polyhedron of a semiregular polyhedron. These shapes are adopted to reduce the surface area relative to the volume of the container. The reason for using the plural segmented members 110 instead of a single member for forming the inner surface 130 is to avoid extreme difficulty in manufacturing the member having a complicated surface with a single ceramic. Even if it is possible to manufacture with the single ceramic, a manufacturing cost for this becomes extremely high.

The “semiregular polyhedron” is ordinarily called “Archimedean solid”. The surfaces of the “Archimedean solid” are formed by plural types of semiregular polyhedrons having the same structure of vertices (totally 13 types). The “semiregular polyhedron” is a “snub dodecahedron” formed by putting together equilateral pentagons (twelve faces) and equilateral triangle (eighty faces) as the faces of the “semiregular polyhedron”, a “truncated icosahedron” (so-called soccer ball shape) formed by putting together equilateral pentagons (twelve faces) and regular hexagons (twenty faces) as the faces of the “semiregular polyhedron”, or the like. The “dual polyhedron of semiregular polyhedron” is called “Archimedean dual”, which is geometry formed by changing between the number of the vertices of the semiregular polyhedron and the number of the faces of the semiregular polyhedron. For example, “Archimedean dual” is a hexakis icosahedron (dual polyhedron of rhombitruncated icosidodecahedron), a deltoidal hexecontahedron (dual polyhedron of rhombicosidodecahedron), and a pentagonal hexecontahedron (dual polyhedron of snub dodecahedron) (See “Solving regular polyhedrons” by Hitotsumatsu Shin, Tokai University Press, in more detail).

Hereinafter, an example of the shape of the segmented member forming the inner surface 130 of the container 100 is described in detail.

FIG. 2A to 2C schematically illustrates a shape of an example segmented member made of a ceramic and used to shape the inner surface of the container. FIG. 2A is a plan view of the segmented member 110 a, FIG. 2B is a side view of the segmented member 110 a, and FIG. 2C is a bottom view of the segmented member 110 a.

As illustrated in FIG. 2A, FIG. 2B and FIG. 2C, the segmented member 110 a is shaped like a column having two bottom surfaces, i.e. a main surface 111 a and a main surface 112 a which are mutually parallel. Both the main surface 111 a and the main surface 112 a upwardly bend as illustrated in FIG. 2B. The main surface 111 a and the main surface 112 a upwardly protrude. It is preferable that the inner surface is designed to form a substantial sphere when plural segmented members 110 a having the same shape are arranged in determining the curvature of the main surfaces. The main surface 111 a is shaped like a pentagon as illustrated in FIG. 2A, and has three short sides LU1 to LU3 having the same lengths and two long sides LU4 and LU5 having the same lengths. The angle θ₁ between two long sides LU4 and LU5 is 67.45° and angles θ₂ between other sides are all 118.14°. A length ratio between the longer side and the shorter side is 1:1.75. In a similar manner, the main surface 112 a is shaped like a pentagon as illustrated in FIG. 2C, and has three short sides LD1 to LD3 having the same lengths and two long sides LD4 and LD5 having the same lengths. A relationship between the sides and the angles among the sides of the main surface 112 a is the same as the relationship between the sides and the angles among the sides of the main surface 111 a. Referring to FIG. 2A to FIG. 2C, the main surface 112 a has a reduced shape of the shape of the main surface 111 a while maintaining a similar figure to the main surface 111 a. Therefore, five side surfaces 113 slope from the main surface 111 a to the main surface 112 a as illustrated in FIG. 2B. Referring to FIG. 2B, an angle θ₃ between ridge lines of the side surfaces 113 and a plumb from the main surface 112 a to the main surface 111 a is about 10°. However, this is an example, and the angle θ₃ may be different as long as the two adjacent segmented members can be arranged without interference between the two adjacent segmented members.

The main surfaces 11 a and 112 a do not necessarily have the curved shapes and may have flat shapes. It is significant that the main surface, especially the main surface 112 a, has the curved face as illustrated in FIG. 2A to FIG. 2C, because the volume formed by being surrounded by the inner surface of the arranged segmented members may become even larger.

By lengthwise and crosswise arranging as many as sixty of these segmented members 110 a, it is possible to form the inner surface 130 of the container having a substantially sphere-like surface. When the main surfaces 111 a and 112 a of the segmented members 110 a have flat faces which are not curved faces, the inner surface 130 of the container is formed to be a substantial pentagonal hexecontahedron as illustrated in FIG. 3. Referring to FIG. 3, only the main surfaces 111 a of the segmented members 110 a can be observed. It is necessary to note that the actual inner surface 130 of the container is formed by the unobservable main surfaces 112 a of the segmented members. Said differently, referring to FIG. 1, the observable shape is on the surfaces of the segmented members which are in contact with the inorganic filler 107.

FIG. 4 illustrates an enlarged view of a part of the container 100 formed by arranging the segmented members 110 a on the inner surface of the casing 105. Referring to FIG. 4, the inorganic filler 107 is provided in gaps between the casing 105 and the segmented members 110 a and gaps among the segmented member 110 a. By arranging the segmented member as such, it is possible to form the inner surface 130 of the container to be a substantial sphere or a substantial pentagonal hexecontahedron.

A sheet material including inorganic fiber may be provided in gaps between the casing 105 and the segmented members 110 a and/or gaps among the segmented members 110 a in place of the inorganic filler 107. The sheet material including the inorganic fiber is generally bulky and flexible. Therefore, when this sheet material is used, the segmented member 110 a can be mechanically in contact with or engaged with the seat member by pressing the segmented member 110 a on the seat member. When the segmented member 110 a is broken, the broken segmented member can be easily removed by drawing the broken segmented member out from the seat member. Therefore, it becomes possible to change the segmented member more easily in comparison with a case of using the inorganic filler 107 in the gaps. When sufficient adhesiveness is not obtainable while the segmented member 110 a is being pressed on the seat member, an inorganic adhesive may be used between the segmented member 110 a and the seat member.

The material of the inorganic fiber contained in the seat member is not specifically limited and may be alumina, silica or a mixture of these. The mode of the seat member is not specifically limited and May be various such as a mode of mat formed by an inorganic fiber and a mode of unwoven fabric.

The shape of the segmented member used for forming the inner surface 130 is not limited to those illustrated in FIG. 2A to FIG. 2C. For example, other segmented members may be put together to form a substantially sphere-like inner surface 130. Further, the segmented members may be put together to form the inner surface having a substantial semiregular polyhedron shape. Further, the segmented members may be put together to form the inner surface having a substantial dual polyhedron of semiregular polyhedron shape, which is different from that illustrated in FIG. 3.

Referring to FIG. 5, an inner surface having a shape of a substantial semiregular polyhedron (snub dodecahedron) may be formed by putting together segmented members 110 d of equilateral triangles and segmented members 110 e of equilateral pentagons.

Referring to FIG. 6( a), the inner surface of a so-called “deltoidal hexecontahedron” (one type of a dual polyhedron of a semiregular polyhedron) may be formed by putting together the segmented members 110 b. Referring to FIG. 6( b), an expansion view of “deltoidal hexecontahedron” is illustrated to facilitate understanding of the shape illustrated in FIG. 6( a). In the “deltoidal hexecontahedron”, main surfaces are formed by two kite-like shapes (rectangle) having two even shorter sides and two even longer sides. A ratio of the shorter side and the longer side is 1:1.54.

Referring to FIG. 7( a), the inner surface of a so-called “hexakis icosahedron” (one type of a dual polyhedron of semiregular polyhedron) may be formed by putting together the segmented members 110 c. Referring to FIG. 7( b), an expansion view of “hexakis icosahedron” is illustrated to facilitate understanding of the shape illustrated in FIG. 7( a). In the “hexakis icosahedron”, the main surfaces are formed by inequilateral triangles, and a ratio of the lengths of three sides of the inequilateral triangle is 1:1.57:1.85.

As described, in the present invention, by putting together plural segments, it is possible to form the container substantially having the inner surfaces of the sphere, the semiregular polyhedron, and the dual polyhedron of semiregular polyhedron.

Hereinafter, reviewed is a relationship between the volume V of the inner spaces and the surface area S of the inner surfaces of a container having a cylindrical inner surface (hereinafter, simply referred to as a cylindrical container) and a container having an inner surface which is shaped substantially like a sphere, a semiregular polyhedron, and a dual polyhedron of semiregular polyhedron (hereinafter, simply referred to as a spherical container).

For example, a container which can accommodate molten metal of about 1 ton inside the internal space of the container is examplified. In this case, the necessary volume V of the internal space is about 0.37 m³ because the specific gravity of aluminum is about 2.7 g/cm³.

In case of the “cylindrical container”, if the volume of the internal space is constantly V (0.37 m³), the surface area S₁ changes along with changes of the radius r₁ and the height H of the circle on the bottom surface of the “cylindrical container”. When the radius r₁ of the circle on the bottom surface of the “cylindrical container” is changed, the heights H are determined respectively for the radii r₁ of the circle, and the surface areas S₁ are determined for the radii r₁. FIG. 8 illustrates a change of the surface area S₁ relative to the change of the radius the r₁ of the circle on the bottom surface of the “cylindrical container”. The axis of ordinate represents S₁/V obtained by dividing the surface area S₁ with the volume V of the internal space. Referring to FIG. 8, it is known that the surface area S₁ is minimized when the radius r₁ of the circle on the bottom surface of the “cylindrical container” is about 0.4 m. At this time, the value of the S/V is about 7.7 m⁻¹.

Referring to FIG. 4, the “substantially spherical container” has an inner surface formed by putting together the segmented member 110 a illustrated in FIG. 2A, FIG. 2B and FIG. 20. When a sphere in contact with the inner surface of the container is imagined, the radius R₂ of the sphere enabling to obtain the volume V of the internal space is calculated to be about 0.45 m and the surface area S2 is calculated to be about 2.49 m². In this case, the above S/V value becomes 6.73 m⁻¹. The black circle of FIG. 8 indicates the above case. Referring to FIG. 8, it is known that the S/V value is restricted to be small in comparison with any cases of the “cylindrical container”.

Referring to FIG. 9, the axis of ordinate of the graph represents a change rate P of the surface area S₁ relative to the surface area S₂ of the “substantially sphere-like container” as a result of a similar analysis to that illustrated in FIG. 8. Here, the following relationship is established.

Change rate P(%)={(S ₁ −S ₂)/S ₁}×100

Referring to FIG. 9, when the volume V is constant, it is known that the surface area S₂ of the “substantially spherical container” is restricted to be smaller than any surface area S₁ of the “cylindrical container” (the change rate P is in the position 0 of the axis of ordinate when the surface area the surface area S₂ is the surface area S₁). Particularly, in comparison with a case where the surface area S₁ of the “cylindrical container” is the smallest (the radius r₁ is about 0.4 m), the surface area S₂ of the “substantially sphere-like container” is still smaller by about 13%.

As described, in the container of the present invention, the inner surface is substantially formed to be a sphere, a semiregular polyhedron or a dual polyhedron of a semiregular polyhedron. Therefore, it is possible to significantly restrict a dissipative heat loss from the container.

It is preferable that the segmented members 110 made of ceramic have a cavity.

Ordinarily, a thermal flux q flowing from one space (e.g. internal space) to the other space (e.g. external space) via a wall composed of plural members 1, 2, . . . , i is represented by the following formula.

$\begin{matrix} {{Formula}\mspace{14mu} 1} & \; \\ {q = {\frac{1}{k}\left( {\theta_{f\; 1} - \theta_{f\; 2}} \right)}} & (2) \end{matrix}$

, where θ_(f1) designates a temperature of an internal space and θ_(f2) designates a temperature of an external space.

$\begin{matrix} {{Formula}\mspace{14mu} 2} & \; \\ {k = {\frac{1}{\frac{1}{h_{1}} + {\sum\frac{\delta_{i}}{\lambda_{i}}} + \frac{1}{h_{2}}}\left( {W\text{/}{m^{2} \cdot K}} \right)}} & (3) \end{matrix}$

Here, an inverse number of k is called thermal resistance. Further, h₁ designates a coefficient of heat transfer of an internal space of the wall, h₂ designates a coefficient of heat transfer of an external space of the wall, δ_(i) designates the thicknesses of coatings forming the wall constituted by plural members, and λ_(i) designates the thermal conductivities of the coatings.

Next, a case where the wall is formed by only the ceramic member (e.g. silicon nitride) and a case where the wall has two layered structure including the ceramic member (e.g. silicon nitride) and an air coating is considered. The thermal conductivity λ of air is about 0.03 W/m·K and the thermal conductivity λ of silicon nitride is about 30 W/m·K. Therefore, referring to Formula (2) and Formula (3), when the wall has the two-layered structure, k becomes even smaller in comparison with a case where the wall has the single coating of ceramic. Therefore, by providing the air coating, the thermal flux q becomes even smaller and the thermal resistance of the wall is improved.

Therefore, in the present invention, when the segmented member 110 made of ceramic has a cavity, it becomes possible to further restrict dissipative heat loss from the container. When the segmented member 110 having the cavity is used, it is possible to restrict the entire weight of the container. Therefore, handling and delivery of the container becomes easy to thereby more easily carry out the delivery. Air may be supplied in the cavities of the segmented members. The cavity may be instead depressurized or evacuated as practiced by one ordinarily skilled in art.

The segmented member may be preferably formed by a chemically stable material when the segmented member is in contact with molten metal. With this, it is possible to restrict a problem that the quality of the molten metal is degraded by impurities mixed into the molten metal with a cross reaction between the molten metal and the segmented member. Further, it is possible to diminish a problem such as breakage of the container caused by chemical deterioration.

When the above segmented member has the cavity, the wall thickness of the member is preferably as thin as possible from a viewpoint of thermal shock resistance.

For example, when the strength of a material is σ_(f) and thermal stress is σ_(th), destruction caused by the thermal stress occurs when a relationship of σ_(f)=σ_(th) is established. Therefore, a critical temperature difference ΔT_(c) at which the material can endure may be determined by the following formula.

$\begin{matrix} {{Formula}\mspace{14mu} 3} & \; \\ {{\Delta \; T_{C}} = {\frac{1.451\; {\sigma_{f}\left( {1 - v} \right)}}{\alpha \; E}\left( {1 + \frac{3.41}{\beta}} \right)}} & (4) \end{matrix}$

, where ν designates a Poisson's ratio, E designates a Young's modulus, α designates a coefficient of thermal expansion, and β designates a Blot coefficient. The blot coefficient is a dimensionless number expressed by the following formula (5), where λ designates the thermal conductivity of the material, δ designates the thickness of the material, and h designates the coefficient of heat transfer.

β=Δh/λ  (5)

It is known from the formula (5) that the smaller thickness of the material is, the smaller β is and the larger ΔT_(c) is.

On the other hand, extreme thinning of the wall of the segmented member having the cavity may cause a problem because the mechanical strength of the segmented member is lowered. Therefore, in a case of the segmented member having the cavity, the wall thickness may be preferably in a range of about 1 mm to 10 mm, more preferably about 3 mm to 8 mm.

The ceramic material of the segmented member may be aluminum titanate, silicon nitride, cordierite, spodumene, alumina, silicon carbide, zirconia, sialon, mullite, and boron compound (hereinafter, these ceramics are referred to as “ceramic of non-refractory brick”). Especially, because aluminium titanate and silicon nitride are stable to an aluminum molten metal, it is preferable to use aluminium titanate or silicon nitride when the container is used for accommodating the aluminum molten metal.

The ceramic material forming the segmented member may be a refractory brick including one or more materials selected from a group of alumina, magnesia, chromia, silica, and calcia. However, even when the refractory brick is used, it is preferable to use “ceramic of non-refractory brick” for at least the main surface forming the inner surface 130 of the container. Generally speaking, a refractory brick has low strength and is apt to produce a partial crack. However, by employing the above structure of using “ceramic of non-refractory brick” for at least the main surface forming the inner surface 130, the strength of the segmented member becomes high and it is possible to avoid contamination of a liquid accommodated in the internal space of the container.

Further, when the segmented member is made of a metal or an alloy, the material of the segmented member may be an alloy containing Cr and/or Ni such as stainless steel (SUS304, SUS316(L), SUS310S or the like), nickel-based alloy, or the like. In the case of using the segmented member made of the metal or the alloy, in order to restrict a cross reaction between the segmented member and an object such as a liquid accommodated inside the container, it is preferable to install the “ceramic of non-refractory brick” on at least the main surface 112 a forming the inner surface 130 of the container.

The above description has not described well other members forming the container, such as the casing 105 and the inorganic filler 107. However, these members are obviously used in various modes. For example, the outer shape of the casing is not limited to a sphere shape illustrated in FIG. 1, and the casing may have other outline forms such as a rectangular form. Further, the casing may have a double-wall structure, and an air coating, a depressurized coating or a evacuated coating may be provided between the double walls. The material of the casing is stainless steel, nickel-based alloy or the like. On the other hand, the inorganic filler may be an inorganic material of alumina-silica (for example, a castable material).

Second Mode

FIG. 10 schematically illustrates a second container of the present invention. The second container 1000 basically has a similar structure to the container 100 illustrated in FIG. 1. Therefore, the same reference symbols as those in FIG. 1 are given to the members illustrated in FIG. 10 similar to members illustrated in FIG. 1.

However, in the second container 1000, a discharge spout corresponding to the discharge spout 160 of FIG. 1 is not provided. When a top lid 1050 of the second container 1000 is closed, a continuous inner surface 1030 is formed and an internal space 1035 is completely and hermetically closed.

In comparison with the container having the discharge spout 160 illustrated in FIG. 1, the second container 1000 has a smaller surface area contributing to heat dissipation to thereby enhance thermal resistance of the container more. By inclining the second container 1000, an object accommodated in the internal space can be discharged from an opening formed when the top lid 1050 is opened. In the second container 1000, an introduction spout used to accommodate the object into the internal space 1035 is the same as a discharge spout used when the object is discharged from the internal space 1035.

In the second container 1000, the inorganic filler 1007 may be replaced by a sheet material including an inorganic fiber as described above.

Next, the effects of the embodiments of the present invention are described in detail.

Embodiment 1

A silicon nitride powder (the average particle diameter of about 1 μm), an alumina powder (the average particle diameter of about 1 μm) and an yttria powder (the average particle diameter of about 1 μm) were measured to have a weight ratio of 92:3:5, and these powders were sufficiently mixed. Acrylic binder of 0.5 wt % for the weight of the mixed powders and water of 140 wt % for the weight of the mixed powders (without the acrylic binder) were mixed with the mixed powders. These mixed powders, acrylic binder, and water were mixed by a ball mill.

The obtained slurry was poured into a gypsum mold. The gypsum mold had a top lid and an inner surface of an upper, lower, right and left surfaces were determined so that molded bodies having shapes illustrated in FIG. 2A, FIG. 2B and FIG. 2C were obtainable. The top lid of the gypsum mold has a discharge spout of 10 mm in its diameter was provided to discharge non-solidified slurry. After the slurry of about 5 mm was adhered to the gypsum mold, the non-solidified slurry was discharged to thereby obtain a molded body having a cavity.

After drying the molded body, the molded body was burned for 3 hours at a maximum temperature of 1800° C. under a nitrogen atmosphere of 0.93 MPa. Thus, the segmented member having a shape illustrated in FIG. 2A, FIG. 2B and FIG. 2C was obtainable. The length of the longer side (LU4 and LU5 of FIG. 2A, FIG. 2B and FIG. 2C) of the first main surface of the obtained segmented member was 122.5 mm, and the length of the shorter side (LU1 to LU3 of FIG. 2A, FIG. 2B and FIG. 2C) thereof is 70 mm. The length of the longer side (LD4 and LD5 of FIG. 2A, FIG. 2B and FIG. 2C) of the second main surface of the obtained segmented member is 88.2 mm, and the length of the shorter side (LD1 to LD3 of FIG. 2A, FIG. 2B and FIG. 2C) thereof is 50 mm. The wall thickness is about 5 mm, and the height (length G of FIG. 2A, FIG. 2B and FIG. 2C) is 90 mm.

When the obtained segmented members were observed by eyes, there was no abnormality such as a crack.

Embodiment 2

An aluminum titanate powder (the average particle diameter of about 1 μm), an acrylic binder of 1 wt % for the weight of the powder, and water of 160 wt % for the weight of the powder (without the acrylic binder) were mixed by a ball mill. The obtained slurry was poured into a gypsum mold. With this process, a molded body having a cavity was obtained.

After drying the molded body, the molded body was burned for 2 hours at a maximum temperature of 1400° C. under an air atmosphere. Thus, a sintered compact was obtained. The dimensions of the sides are similar to those in Embodiment 1. A sample having a thickness of 1 mm and a diameter of 10 mm was cut out from the sintered compact. This sample was used to determine its thermal conductivity by using a laser flash measurement (measuring, equipment: TC-7000 manufactured by ULVAC-RIKO Inc.) It was known that the thermal conductivity of the sample is about 1 W/m·k which was sufficiently small. As a result of the experiment, the sample is hardly wetted by an aluminum molten metal.

Embodiment 3

A silicon nitride powder (the average particle diameter of about 1 μm), an acrylic binder of 1 wt % for the weight of the powder, and water of 160 wt % for the weight of the powder were mixed by a ball mill. A molded body was formed from the obtained slurry by a method described in Embodiment 1. After drying the molded body, the molded body was burned for 5 hours at a maximum temperature of 1400° C. under a nitrogen atmosphere. Thus, the segmented member having a shape illustrated in FIG. 2A, FIG. 2B and FIG. 2C was obtained. The dimensions of the sides are similar to those in Embodiment 1.

Embodiment 4

An alumina powder AL-160SG4 (the average particle diameter of about 1 μm) of a weight of 100, a dispersed material A6114 of a weight of 0.75, and water of a weight of 160 were mixed. An acrylic binder of 1 wt % was added to the above mixture. After mixing with a ball mill for 16 hours, a process of ejecting bubbles was applied to the mixture. A molded body was formed using the obtained slurry in a similar manner to that of Embodiment 1. After drying the molded body, the molded body burned for 2 hours at a maximum temperature of 1600° C. under a nitrogen atmosphere. Thus, the segmented member having a shape illustrated in FIG. 2A, FIG. 2B and FIG. 2C was obtained. The dimensions of the sides are similar to those in Embodiment 1.

Segmented members are made of sialon, silicon carbide, silica, cordierite, spodumene, and boron nitride respectively with a similar manner to the above. All these segmented members were wetted by an aluminum molten metal to thereby prove chemical stability of the these segmented members to the aluminum molten metal.

Embodiment 5

A container having a substantially spherical shape was made. An outside of the container (i.e. casing) was made of stainless steel (SUS304) having a thickness of 8 mm. The casing was made of two pieces. The dimensions of the assembled stainless steel casing are 940 mm in the outer diameter and 924 mm in the inner diameter. Inside the casing, the segmented members made of the silicon nitride obtained in Embodiment 1 were arranged by interposing an inorganic filler (castable material) having a major component of alumina-silica in a shape illustrated in FIG. 3 inside the casing to thereby form the inner surface of the container. By using the as many as 60 of the segmented members, it was possible to form the inner surface having a substantial sphere. The similar inorganic filler was provided in gaps formed among the segmented members. A sphere presumably circumscribed by the inners surface of the above container has the radius of about 450 mm. The container can accommodate an aluminum molten metal of about 1 ton.

Embodiment 6

In a similar manner to Embodiment 5, a container having a substantially spherical shape was made. With Embodiment 6, the segmented members made of aluminium titanate according to Embodiment 2 were used.

Embodiment 7

An alumina brick (CWK-3 manufactured by AGC Ceramics Co., Ltd.) mainly made of a commercially available electro-fused material of corundum mullite type was cut and processed to manufacture the segmented member having the shape illustrated in FIG. 2A, FIG. 2B and FIG. 2C. The segmented members do not have a cavity in Embodiment 7. The specific gravity of the alumina brick is about 2.1.

A sample having a thickness of 1 mm and a diameter of 10 mm is cut out from the alumina brick. This sample is used to determine the thermal conductivity by using a laser flash measurement (measuring equipment: TC-7000 manufactured by ULVAC-RIKO Inc.). The thermal conductivity of the sample is about 1.2 W/m·K.

Embodiment 8

A magnesia-chrome brick (NSX-750 manufactured by AGC Ceramics Co., Ltd.) was cut and processed to manufacture the segmented member having the shape illustrated in FIG. 2A, FIG. 2B and FIG. 2C. The segmented members do not have a cavity in Embodiment 8. The specific gravity of the magnesia-chrome brick is about 1.8.

A sample having a thickness of 1 mm and a diameter of 10 mm was cut out from the magnesia-chrome brick. This sample was used to determine the thermal conductivity by using a laser flash measurement (measuring equipment: TC-7000 manufactured by ULVAC-RIKO Inc.) The thermal conductivity of the sample is about 1.0 W/m·K.

Embodiment 9

After pouring an alumina cement into a gypsum mold, the alumina cement was solidified at room temperature to thereby form the segmented member having the shape illustrated in FIG. 2A, FIG. 23 and FIG. 2C. The segmented members do not have a cavity in Embodiment 9. Before the alumina cement was poured into the gypsum mold, a plate having an anchor made of silicon nitride was installed inside the gypsum mold.

FIG. 11A to FIG. 11C illustrates a schematic shape of the segmented member after the alumina cement was solidified. The plate 340 having the anchor has a bottom portion 345 having a large surface 343 and an anchor portion 350 connected to the bottom portion 345, and is substantially shaped like “H”. When the alumina cement 360 was poured into the gypsum mold, the plate 340 was installed in the gypsum mold so that the large surface 343 of the plate 340 having the anchor forms the main surface 112 a of the segmented member.

Embodiment 10

A commercially available FeCrNi alloy 32Cr-43Ni (KHR45A manufactured by Kubota Corporation) was cut and processed to make the segmented member having the shape illustrated in FIG. 2A to FIG. 2C. However, the main surface 111 a of the segmented member does not exist in Embodiment 10 (the segmented member has a box-like shape without one surface). The thickness of the main surface 111 b of the segmented member is 3 mm, and the thickness of the sidewall is 2 mm. After the main surface 111 b was subjected to shotblasting, a zirconia sprayed coating is provided on the main surface. The zirconia sprayed coating was formed by plasma spraying, and the thickness of the zirconia sprayed coating is about 100 μm.

Embodiment 11

In a similar manner to Embodiment 5, a container having a substantially spherical shape was made. With Embodiment 11, the segmented members made of aluminium titanate according to Embodiment 7 were used.

Embodiment 12

In a similar manner to Embodiment 5, a container having a substantially spherical shape was made. With Embodiment 12, the segmented members made of alumina cement using the plate made of silicon nitride according to Embodiment 9 were used.

Embodiment 13

In a similar manner to Embodiment 5, a container having a substantially spherical shape was made. With Embodiment 13, the segmented members made of alumina cement using the plate made of silicon nitride according to Embodiment 10 were used.

Comparative Example 1

A container having a cylindrical internal space was made. A schematic cross-sectional view is illustrated in FIG. 12. The container 200 having a casing 205 is made of stainless steel (SUS304) and has a thickness of 8 mm. An inorganic adhesive coating (alumina-silica), an inorganic fiber coating (alumina-silica), and a refractory cement coating (castable) 207 are provided on the entire inner surface of the casing in this order. The refractory cement coating 207 becomes an inner surface 230 of the container to shape the internal space 235. Referring to FIG. 12, only the casing 205 and the refractory cement coating 207 are illustrated for clarification. The radius r₁ of the bottom surface of the internal space is about 0.4 m and the height H of the container is about 0.74 m. The container can accommodate aluminum molten metal of about 1 ton.

The thermal resistance of the containers of Embodiments 5 and 6 and Comparative Example 1 were evaluated. The evaluation was done by measuring the temperatures of corresponding aluminum molten metal materials after a passage of a predetermined time (one hour) from a state in which the aluminum molten metal materials having an initial temperature of 750° C. of about one ton are poured into internal spaces of the containers and the internal spaces are hermetically closed. The results are illustrated in Table 1.

TABLE 1 TEMPERATURE OF MOLTEN METAL AFTER PASSAGE OF STRUCTURE ONE HOUR (° C.) EMBODIMENT 1 722 EMBODIMENT 2 734 COMPARATIVE EXAMPLE 1 675

From Table 1, it is known that the temperature of the molten metal material in the container of Comparative Example 1 decreases down to 675° C. after one hour. In comparison, the temperatures of the aluminum molten metal materials in the containers of Embodiments 5 and 6 are maintained to be 722° C. and 734° C., respectively. It was confirmed that dissipative heat loss is significantly restricted in comparison with the conventional container.

Table 2 illustrates evaluation results of the thermal resistance of the containers of Embodiments 11, 12 and 13. In a similar manner to the above, the evaluation was done by measuring the temperature of aluminum molten metal materials after a passage of a predetermined time (one hour) from a state in which the aluminum molten metal materials having an initial temperature of 750° C. of about one ton were poured into internal spaces of the containers and the internal spaces were hermetically closed.

TABLE 2 TEMPERATURE OF MOLTEN METAL AFTER PASSAGE OF STRUCTURE ONE HOUR (° C.) EMBODIMENT 11 708 EMBODIMENT 12 721 EMBODIMENT 13 719

In comparison, the temperatures of the aluminum molten metal materials in the containers of Embodiments 11 and 13 are maintained to be within a range of between 708° C. and 721° C. It is confirmed that dissipative heat loss is significantly restricted in comparison with the conventional container.

INDUSTRIAL APPLICABILITY

The present invention may be applicable to a container for accommodating a metal such as aluminum, magnesium, and zinc and alloys of these metals. The present invention is applicable to not only the molten metal but also a container for accommodating a high temperature powder, pellets or the like.

This patent application is based on Japanese Priority Patent Application No. 2008-214409 filed on Aug. 22, 2008, the entire contents of which are hereby incorporated herein by reference.

EXPLANATION OF REFERENCE SIGNS

-   100: Container; -   105: Casing; -   107: Inorganic filler; -   110: Segmented member; -   110 a, b, c, d, e: Segmented member; -   111 a, 112 a: Main surface; -   113: Side surface; -   130: Inner surface; -   135: Internal space; -   200: Container; -   205: Casing; -   207: Inorganic filler; -   230: Inner surface; -   235: Internal space; -   1000: Second container; -   1005: Casing; -   1007: Inorganic filler; -   1010: Segmented member; -   1030: Inner surface; -   1035: Internal space; and -   1050: Top lid. 

1. A container which can accommodate an object inside an internal space shaped by an inner surface of the container, wherein the inner surface substantially has a shape of a sphere, a semiregular polyhedron or a dual polyhedron of a semiregular polyhedron, and the inner surface is formed by a plurality of segmented members made of a refractory material.
 2. The container according to claim 1, wherein the refractory material of the container may be a refractory metal or a refractory alloy.
 3. A container which can accommodate an object inside an internal space shaped by an inner surface of the container, wherein the inner surface substantially has a shape of sphere, a semiregular polyhedron, or a dual polyhedron of semiregular polyhedron, and the inner surface is formed by a plurality of segmented members made of a ceramic.
 4. The container according to claim 1, wherein a value of S/V (m) is lower than 7.7 m⁻¹ where a volume of the internal space is V (m³) and a surface area of the inner surface is S (m²).
 5. The container according to claim 1, wherein the semiregular polyhedron is substantially configured by a combination of an equilateral triangle and an equilateral pentagon.
 6. The container according to claim 1, wherein the dual polyhedron of the semiregular polyhedron is a pentagonal hexecontahedron, a deltoidal hexecontahedron, or a hexakis icosahedron.
 7. The container according to claim 1, wherein the segmented members may have a main surface of a curved face and a second surface of a curved face, the main surface and the second surface being substantially parallel each other.
 8. The container according to claim 1, wherein the segmented members have a cavity.
 9. The container according to claim 3, wherein the ceramic is made of one or more materials selected from a group of aluminum titanate, silicon nitride, cordierite, spodumene, alumina, silicon carbide, zirconia, sialon, mullite, and boron compound.
 10. The container according to claim 3, wherein the ceramic is a refractory brick including one or more materials selected from a group of alumina, magnesia, chromia, silica, and calcia.
 11. The container according to claim 1, wherein a first inorganic filler is provided among the segmented members in the container.
 12. The container according to claim 1, wherein a sheet material including an inorganic fiber is provided among the segmented members of the container.
 13. The container according to claim 12, wherein the inorganic fiber includes alumina.
 14. The container according to claim 1, further comprising: a easing surrounding the segmented members; and a second inorganic filler installed between the casing and the segmented members.
 15. The container according to claim 1, further comprising: a casing surrounding the segmented members; and a sheet material including the inorganic fiber installed between the casing and the segmented members.
 16. The container according to claim 15, wherein the inorganic fiber contains alumina.
 17. The container according to claim 1, wherein the object is a molten metal.
 18. The container according to claim 1, wherein a material different from a material forming the segmented members is installed on at least one surface of the segmented members.
 19. The container according to claim 2, wherein a ceramic is installed on at least one surface of the refractory material.
 20. The container according to claim 1, wherein the internal space is a space substantially hermetically closed.
 21. (canceled) 